net: xilinx: axienet: Use NL_SET_ERR_MSG instead of netdev_err

This error message can be triggered by userspace. Use NL_SET_ERR_MSG so
the message is returned to the user and to avoid polluting the kernel
logs. Additionally, change the return value from EFAULT to EBUSY to
better reflect the error (which has nothing to do with addressing).

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Link: https://lore.kernel.org/r/20240611154116.2643662-1-sean.anderson@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1945,9 +1945,9 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
 	struct axienet_local *lp = netdev_priv(ndev);
 
 	if (netif_running(ndev)) {
-		netdev_err(ndev,
-			   "Please stop netif before applying configuration\n");
-		return -EFAULT;
+		NL_SET_ERR_MSG(extack,
+			       "Please stop netif before applying configuration");
+		return -EBUSY;
 	}
 
 	if (ecoalesce->rx_max_coalesced_frames)